Maximum Yield of Wood

A typical example for practical cutting problems considered in the optimization department is the problem of minimizing waste in sawmills, where boards of different grades and different dimensions are cut from logs.

Cutting Problems

An integral part of many production processes is the cutting of blanks into products. In the wood processing industry, for example, logs and shelves are sawn, in the metalworking industry different components are stamped out of metal plates, and in a variety of industries coils of different materials are tailored. For all these jobs, quite different cutting tools are used. In many applications, however, the blank cannot be completely converted into products, but useless waste is created that ought to be minimized.

We are currently working on several such cutting problems and develop innovative solution methods for various applications. It considers not only the actual cutting problem, but also analyzes it holistically, embedded in the respective production process. 

These approaches go far beyond traditional methods for/of modeling and solving cutting and packing problems, which can be divided roughly into three categories:

  • From a given selection of products, place as many as possible in a blank of fixed dimension.
  • Place a selction of products in a blank of minimal size. The size and shape of the blank are, subject to certain restrictions, variable.
  • Place a selection of products in a minimum number of blanks of fixed dimension.

Project Example: Cross-section Optimization for Sawmills

One of the main tasks in large sawmills is the selection of suitable sectional views for the production of boards and beams. Therefor complex technical requirements of the saws, the available logs, and economic aspects need to be considered. Since it is often impossible to meet all objectives best possible, one hat to weigh the alternatives and select a good compromise.

To cope with this planning task the ITWM developed a decision support system that provides a consistent look at a variety of different sectional views and shows such views representing sensible compromises between different objectives. In particular, the inclusion of economic considerations allows it to better match production to market requirements. It is often usefull to prefer better saleability over maximizing volume utilization.

The system can be adapted to different requirements of various sawing lines and is based on established decision-making processes in sawmills.

PABC-Schnittbild
© Photo ITWM

Sectional view with maximum yield